This invention relates to video decoding on personal computers.
MPEG video has become widely accepted as a standard for video. The original protocol, MPEG1, is in widespread use, and a new, higher-quality standard, MPEG2, is being introduced. Typically, MPEG1 decoding performed on personal computers is done using software, as software decoding is much less expensive than hardware decoding, which requires a dedicated video decoder board. Today's high-speed processors (e.g., a 90+ MHz Pentiums) make such software decoders possible. But at 30 frames per second, such decoders are forced to resort to approximating some of the MPEG1 decoding steps (e.g., dequantizing, IDCT, motion compensation), as they cannot otherwise decode quickly enough to keep up with the incoming video. The result is noticeably degraded video quality.
Limited reliance has been placed on the graphics coprocessor chip (sometimes referred to as a graphics accelerator chip) in MPEG video decoding. The graphics coprocessor's role has been to convert the decoded video from YUV to RGB format and to scale the images to a desired size.
MPEG2 decoding will require about 4 times the computing resources required for MPEG1, making it likely that software decoding (with RGB transformation and scaling done by the accelerator chip) will not be feasible. This suggests that it will be necessary to use hardware decoders, e.g., dedicated video boards or chips, to handle MPEG2 decoding.